Directional poppet valve

ABSTRACT

The invention relates to a directional poppet valve ( 10 ), comprising valve pistons ( 16 - 22 ) arranged in a valve housing ( 12 ) for controlling a plurality of fluid connections (A, B, P, T), wherein the positions of each of the valve pistons ( 16 - 22 ) in the valve housing ( 12 ) can be changed by means of at least one actuating device, and wherein the fluid connections (A, B, P, T) are connected to one another or separated from one another alternately depending on the position of the valve pistons ( 16 - 22 ). The invention is characterised in that the valve pistons ( 16 - 22 ) are arranged inline along at least one axis (R), consecutively and/or at least such as to partially interengage, in the valve housing ( 12 ).

The invention relates to a directional poppet valve, comprising valvepistons disposed in a valve housing for controlling a plurality of fluidconnections, wherein the positions of each of the valve pistons in thevalve housing can be changed by means of at least one actuation device,and wherein the fluid connections are alternately connected with oneanother or separated from one another depending on the placement of thevalve pistons.

Directional poppet valves are known in different structural designs. Inknown directional valves, the poppet valve cartridge cannot be fullyforce balanced, which results in a loss of performance and the need forincreased actuation forces. Sometimes the structural design of the knowndirectional poppet valves is so costly and prone to failure thatcomplicated actuation mechanisms and a complicated drilling path in theblock must be implemented for the actuation. In addition, a definedopening of control edges as well as a positive or negative overlap ofcontrol edges is only possible with great difficulty or is not possibleat all. In addition, in known directional poppet valves, the fluidpressures must be selected in such a way that the pump pressure in thesupply connection exceeds the consumer load pressure in the respectiveutility connection, and this load pressure in turn must exceed the tankpressure in the tank connection.

The object of the invention is to provide a directional poppet valvethat is as force balanced as possible, which can be actuated in a simplemanner and with low actuation forces, and which has improved controlfunctions.

This object is achieved by a directional poppet valve having thefeatures of claim 1 in its entirety. A directional poppet valveaccording to the invention is characterized by the fact that the pistonvalves in are disposed in a so-called inline construction, one after theother along at least one axis and/or in the valve housing such that theyat least partially interengage.

According to the invention, two or more valve pistons are disposed inthe piston chamber, which extends along the at least one axis in thevalve housing, which valve pistons may be moved or displaced along therespective axis. The respective actuation device provided for thispurpose may be designed for electric actuation, for example as anelectromagnet or as a step or linear motor respectively, may be designedfor mechanical actuation or for manual actuation. In addition, it isconceivable that the directional poppet valve according to the inventionmay be operated by means of proportional and/or switching magnets, or inother words, that the respective valve piston may be actuated in such amanner.

The arrangement of the valve pistons according to the invention makes asimple production and a compact design of the directional poppet valveaccording to the invention possible. An at least partial interengagementof each of a plurality, typically two valve pistons, allows theinstallation space, or more precisely the piston chamber provided in thevalve housing, to be designed such that it is smaller in comparison withconventional solutions. Depending on the intended use of the directionalpoppet valve according to the invention, this valve may be designed as a3/2-directional poppet valve, as a 4/2-directional poppet valve or as a4/3-directional poppet valve for example. Due to the comparatively shortadjustment or actuating travel of the respective valve piston, therespective, for example three or four, fluid connections correspondingto the desired switch positions may be connected to one another suchthat they can carry fluid, or may be separated from one another such ina fluid-tight manner.

In a preferred embodiment of the directional poppet valve according tothe invention, the piston valves interengage in pairs, preferably eachdisposed between two seats, and can be moved relative to one another bymeans of a respective resetting device, preferably in the direction ofone respective seat. The advantage of this embodiment lies in the factthat, when viewed in the direction of the axis, the piston valves can bedisposed in a short piston chamber in a space-saving manner. Theresetting device allows the piston valves to be moved towards and apartfrom one another, so that in the non-actuated state, i.e., without theapplication of an actuation force by the respective actuation device,the piston valves abut the respective seats thereof. The resettingdevice allows the contact force, or the contact pressure, respectively,to be specified for the respective valve piston at the respective seat.

The piston valves and/or the associated seats are each formed such thatthey are essentially rotationally symmetrical to the axis. The valvepistons may each be designed as conical pistons. This provides theadvantage of a particularly cost-effective implementation of thedirectional poppet valve according to the invention. It is especiallypreferable that the seat for the respective valve piston be formed as anannular surface that is disposed transverse, preferably perpendicular,to the axis, with which annular surface the dedicated end face of therespective valve piston allocated thereto may be in contact, typicallywith a contact force applied by the respective resetting device.

At least one tank connection, at least one supply connection and atleast one utility or consumer load connection may be provided as valveconnections. The fluid connections are connected to the piston chamberencompassing the valve pistons in a fluid-conveying manner, and aretypically each designed as at least one through bore in the valvehousing. The fluid connections of the through bores are advantageouslydisposed such that they extend radially to the axis, which ensures asimple structural design and simple fabrication of the directionalpoppet valve according to the invention.

In an additional preferred embodiment of the directional poppet valveaccording to the invention, the respective actuation device comprises anactuation rod, which acts on at least one valve piston, and/or which atleast partially passes through this valve piston. A particularly simpleand compact design results when the at least one actuation rod extendsalong, or parallel to, the axis, so that complicated constructiveactuation mechanisms may be omitted. The actuation force is transferredto the respective valve pistons by means of the respective actuationrod, and these valve pistons are moved linearly, accordingly, in theselected direction along the axis. In the case of an actuation of thiskind, the corresponding valve piston or pistons is or are spaced awayfrom the respective seat and the corresponding fluid connection isopened. In so doing, the reset force, which is exerted by the respectiveresetting device on the respective valve piston for movement in thedirection of the respective seat, must typically be overcome. Once theactuation is complete, the valve piston is guided back to, and placed incontact with, the respective seat by the reset force exerted by theresetting device, which is typically designed as a spring element.

The respective actuation rod is advantageously guided in the respectivevalve piston, wherein at least one actuator, which actuates at least onevalve piston, is disposed on the respective actuation rod. Such a designof the directional poppet valve according to the invention is especiallyadvantageous when a plurality of, for example, two valve pistons isactuated by means of a shared actuation rod. In the case of two valvepistons, which interengage as a pair, the actuation rod is typicallyguided through both valve pistons and has a first or front, and a secondor rear actuator, which, depending on the direction of movement of theactuation rod relative to the valve piston, abuts a first or front siderespectively, or a second or rear side, respectively, of the pair, or ofthe respective valve piston. The actuators are fixedly attached to theactuation rod or connected thereto respectively, so that an actuationforce can be transferred from the actuation rod to the respective valvepiston by means of the actuator.

In an additional preferred embodiment of the invention, the actuationrods associated with the respective valve pistons are disposed in thevalve housing such that they at least partially interengage. It isespecially preferred that a first and a third actuator be provided on anactuation rod in order to space a first and a third valve piston awayfrom a first or third seat respectively, that a second and a fourthactuator be provided on another actuation rod oriented in the opposingdirection in order to space a second and a fourth piston rod away from asecond or fourth seat respectively, that a first utility connection beprovided between the facing first and second seats for the first andsecond valve pistons, which interengage as a pair, that a second utilityconnection be provided between the facing third and fourth seats for thethird and fourth valve pistons, which interengage as a pair, that asupply connection or a tank connection be provided between the secondseat and the third seat, and that a tank connection, or a supplyconnection, respectively, be provided between the first or fourth seat,respectively, and the respective end of the valve housing.

In this embodiment, the actuation rods for a plurality of valve pistonsare coupled with or to one another, respectively, in such a way that twovalve pistons are each moved or displaced upon the movement of thecorresponding actuation rod and a corresponding switch position of thedirectional valve is adjusted. Thus with the actuation of the oneactuation rod, a fluid connection from the supply connection to thesecond utility connection and an additional fluid connection from thefirst utility connection to the tank connection are opened. Accordingly,with the actuation of the other actuation rod, a fluid connection fromthe supply connection to the first utility connection and an additionalfluid connection from the second utility connection to the tankconnection are opened. It is understood that the tank connection andsupply connection may be exchanged with one another. In a comparablearrangement, three and more utility connections may be connected to tankand supply connections, wherein actuation rods, which act on the valvepistons associated with the respective fluid connections or fluid portsare used.

Further advantages and features of the invention will be apparent fromthe figures and the following description of the drawing. According tothe invention, the above specified, and the additionally cited, featuresmay each be implemented individually or in any combination with oneanother. The features shown in the figures to be understood as purelyschematic and not to scale. Shown are:

FIG. 1 a section through an embodiment of a directional poppet valveaccording to the invention; and

FIG. 2 a circuit symbol for the exemplary directional poppet valve fromFIG. 1.

FIG. 1 shows a section of a directional poppet valve 10 having a valvehousing 12, in the piston chamber 14 of which a first valve piston 16, asecond valve piston 18, a third valve piston 20 and a fourth valvepiston 22 are disposed. The piston chamber 14, having an elongateddesign, extends in the direction of an axis R, which simultaneouslyrepresents a rotational axis for the respective valve piston 16-22. Thefour valve pistons 16-22 are disposed in an inline construction alongthe axis R, wherein the first and the second piston valves 16, 18 aswell as the third and the fourth piston valves 20, 22 are each disposedsuch that they interengage in pairs. The two pairs of in each case twovalve pistons 16, 18; 20, 22 are sequentially disposed along the axis Rin the piston chamber 14.

A seat 17-23 is assigned to each valve piston 16-22, wherein each seat17-23 is formed as an annular surface that is rotationally symmetricalto the axis R, and delimits the front end of the respective receivingsection of the piston chamber 14 in order to receive the one pair,comprising the first and second valve pistons 16, 18, or the other pair,comprising the third and fourth valve pistons 20, 22, respectively. Inthe non-actuated state shown, the piston valves 16-22 each abut therespective seat 17-23. The contact force needed therefor is applied ineach case by a resetting device 34A, 34B, each of which is disposedwithin the valve pistons 16, 18; 20, 22, which interengage in pairs, andguides these valve pistons towards and away from one another to therespective valve seat 17, 19; 21, 23. An annular sealing device 36A, 36Bis disposed between the valve pistons 16, 18; 20, 22 that are connectedto one another in pairs.

Two actuation rods 24A, 24B are provided for the movement of the valvepistons 16-22, which actuation rods are disposed along the axis R in thepiston chamber 14, and which interengage with one another in the regionof the piston chamber 14. The two actuation rods 24A, 24B are each partof an actuation device (not otherwise shown), which each exert anactuation force F_(A), F_(B) on the respective actuation rod 24A, 24B,said actuation force being oriented in one respective direction. Inorder to transfer the actuation forces F_(A), F_(B) from the actuationrods 24A, 24B to the respective piston 16-22, actuators 26-32 areprovided on the two actuation rods 24A, 24B in such a way that the frontend of these actuators each act on the respective valve piston 16-22, inorder to space these pistons away from the respective valve seat 17-23.In the embodiment shown in FIG. 1, the two pairs of valve pistons 16,18; 20, 22 are disposed symmetrically to the (not shown) center plane ofthe piston chamber 14 or of the valve housing 12, respectively, suchthat, by means of an actuation force F_(A) directed towards the right inFIG. 1, the first valve piston 16 can be spaced apart from the firstseat 17 by a first actuator 26, and the third valve piston 20 can bespaced apart from the third valve seat 21 by the third actuator 30.Accordingly, with an opposing actuation force F_(B) directed towards theleft in FIG. 1, the second valve piston 18 can be spaced apart from thesecond seat 16 by the second actuator 28, and the fourth valve piston 22can be spaced apart from the fourth seat 23 by the fourth actuator 32.It should be noted here that the first and the third actuator 26, 30 aredisposed on the one actuation rod 34A shown on the left in FIG. 1 andthe second and the fourth actuator 28, 32 are disposed on the otheractuation rod 24B shown on the right in FIG. 1.

A tank connection T, a first utility connection A, a supply connectionP, a second fluid connection B, and in turn, a tank connection T, areformed sequentially in the valve housing 12 along the piston chamber 14,from left to right in FIG. 1. The first tank connection T and the firstfluid connection A are controlled by the one pair comprising the firstand second valve pistons 16, 18, and accordingly, the second utilityconnection B and the second tank connection T are controlled by theother pair comprising the third and fourth valve pistons 20, 22. Thesupply connection P, which is centrally disposed between the two pairs,is controlled by the adjacent second and third valve pistons 18, 20. Inthe non-actuated state, shown in FIG. 1, of the corresponding switchposition of the directional poppet valve 10, respectively, all of thevalve pistons 16-22 abut the respective seat 17-23, whereby the fluidconnections A-T are separated from one another in as fluid-tight amanner as possible. Due to the symmetrical, uniform design of the valvepistons 16-22, of the valve seats 17-23 as well as of the resettingdevices 34A, 34B or of the respective reset force, the valve arrangementin a non-actuated state is force balanced. The non-actuated switchposition of the directional poppet valve 10 is shown in the center ofthe circuit symbol from FIG. 2.

In the case of an actuation or movement of the one actuation rod 24A,shown on the left in FIG. 1, which movement corresponds to an actuationforce F_(A), the first and the third valve pistons 16, 20 are spacedapart from the first or third seat 17, 21, respectively, andaccordingly, a fluid connection from the first utility connection A tothe tank connection T as well as an additional fluid connection from thesupply connection P to the second utility connection B are opened. Byactuating or moving the one actuation rod 24A , the resetting devices34A, 34B are further compressed, whereby the respective contact pressureof the second and of the fourth valve pistons 18, 22 at the second orthe forth seat 19, 23 is increased accordingly, so that a fluidconnection from the supply connection P to the first utility connectionA, as well as an additional fluid connection from the second utilityconnection B to the tank connection T remains blocked. The switchposition of the directional poppet valve 10 that can be reached by meansof an actuation force F_(A) is illustrated on the left in FIG. 2. At theend of the application of an actuation force F_(A), the two, first andthird, valve pistons 16, 20 are guided back by the resetting devices23A, 34B and abut the first or third seat 17, 21. Accordingly, inaddition to the actuators 26-32, the actuation rods 24A, 24B return totheir respective placement or position in the non-actuated state.

In the case of an actuation or movement of the other actuation rod 24Bshown on the right in FIG. 1, the second and fourth valve pistons 18, 22are spaced apart from the second and fourth seat 19, 23 and accordingly,a fluid connection from the supply connection P to the first utilityconnection A, and an additional fluid connection from the second utilityconnection B to the tank connection T, are opened. By actuating theother actuation rod 24B, the resetting devices 34A, 34B are compressedand consequently the respective contact pressure of the first and of thethird valve pistons 16, 20 at the first or third seat 17, 21 isincreased, and the corresponding fluid connections, from the firstutility connection A to the tank connection T, as well as from thesupply connection P to the second utility connection B, are blocked. Theswitch position of the directional poppet valve 10, corresponding to theactuation of the other actuation rod 24B with the other actuation forceF_(B), is shown on the right in FIG. 2. It can be readily observed inFIG. 2 that the directional poppet valve 10 is a 4/3-directional poppetvalve having three switch positions for fluid connections between fourfluid connections A, B, P, T. At the end of the application of the otheractuation force F_(B), the two, second and fourth, valve pistons 18, 22are guided back by the resetting devices 34A, 34B and abut the secondand fourth seat 19, 23. Accordingly, in addition to the actuators 26-32,the actuation rods 24A, 24B return to their respective placement orposition in the non-actuated state.

The directional poppet valve 10 shown in FIG. 1 is a directly controlledvalve. A pilot-controlled design of the directional poppet valve 10according to the invention is also possible. The fluid pressureavailable at the supply connection P is typically present in theinterior of the valve pistons 16-22, which interengage in pairs, of theinterengaging or meshing actuation rods 24A, 24B respectively, and ofthe actuation devices (not otherwise shown). Depending on the positionof the actuators 26-32, a positive or negative overlap of the controledges may be achieved. In addition, a tolerance compensation may beachieved by the actuators 26-32 such that in a non-actuated state or inother words, in the central position, all valve pistons 16-22 abut therespective seat 17-23 and block the corresponding fluid connections.Depending on the requirements, additional sealing devices may be formedon the valve pistons 16-22. In the embodiment shown, the one actuationrod 24A encompasses the other actuation rod 24B up to the end of the rod25A on the opposing end of the piston chamber 14. Accordingly, the otheractuation rod 24B extends into the one actuation rod 24A, wherein thecorresponding end of the rod is not sown in FIG. 1.

1. a directional poppet valve (10), comprising: valve pistons (16-22)disposed in a valve housing (12) for controlling a plurality of fluidconnections (A, B, P, T), wherein the positions of each of the valvepistons (16-22) in the valve housing (12) can be changed by means of atleast one actuation device, and wherein the fluid connections (A, B, P,T) are alternately connected with one another or separated from oneanother, depending on the placement of the valve pistons (16-22),characterized in that the piston valves (16-22) are disposed one afterthe other along at least one axis (R) and/or in the valve housing suchthat they at least partially interengage (12).
 2. The directional poppetvalve according to claim 1, characterized in that the piston valves(16-22) interengage in pairs, preferably each disposed between two seats(17-23), and can be moved relative to one another by means of aresetting device (34A, 34B), preferably in the direction of onerespective seat (17-23).
 3. The directional poppet valve according toclaim 1, characterized in that the piston valves (16-22) and/or theassociated seat (17-23) are each formed such that they are essentiallyrotationally symmetrical to the axis (R).
 4. The directional poppetvalve according to claim 1, characterized in that at least one tankconnection (T), at least one supply connection (P) and at least oneutility connection (A, B) are provided as fluid connections.
 5. Thedirectional poppet valve according to claim 1, characterized in that therespective actuation device comprises an actuating rod (24A, 24B), whichacts on at least one valve piston (16-22) and/or which at leastpartially passes through these valve pistons, preferably oriented along,or parallel to, the axis (R).
 6. The directional poppet valve accordingto claim 5, characterized in that the respective actuation rod (24A,24B) is guided into the respective valve piston (16-22), and that atleast one actuator (26-32) is disposed on the respective actuation rod(24A, 24B), which actuator acts on at least one valve piston (16-22). 7.The directional poppet valve according to claim 5, characterized in thatthe actuation rods (24A, 24B) allocated to the respective valve pistons(16-22) are disposed in the valve housing (12) such that they are atleast partially interengage.
 8. The directional poppet valve accordingto claims 2, characterized in that a first and a third actuator (26, 30)are provided on an actuation rod (24A), in order to space a first and athird valve piston (16, 20) from a first and third seat (17, 21)respectively, in that a second and fourth actuator (28, 32) are providedon another actuation rod (24B) oriented in the opposing direction, inorder to space a second and a fourth valve piston (18, 22) from a secondor fourth seat (19, 23), respectively, in that a first utilityconnection (A) is provided between the facing first and second seats(17, 19) for the first and second valve pistons (16, 18), whichinterengage as a pair, in that a second utility connection (B) isprovided between the facing third and fourth seats (21, 23) for thethird and fourth valve pistons (20, 22), which interengage as a pair, inthat a supply connection (P) or a tank connection (T) is providedbetween the second seat (19) and the third seat (21), and in that a tankconnection (T), or a supply connection (P), respectively, is providedbetween the first or the fourth seat (17, 23), respectively, and therespective end of the valve housing (12).